Incandescent bodies for electric lamps.



chemist, and FRAN HANAMAN, chemical en-.

1,018,502. No Drawing.

UNITED STATES PATENT OFFICE.

ALEXANDER JUST AND FRANZ HANAMAN, OF BUDAPEST, AUSTRIA-HUNGARY, AS- SIGNOBS, BY DIRECT AND MESNE ASSIGNMENTS, TO GENERAL ELECTRIC COM- PANY, A CORPORATION OF NEW YORK INCANDE SCENT BODIES FOR ELECTRIC LAMPS.

Specification of Letters Patent. Application filed m re i905. Beria1No..268,523.

Patented Feb; 27, 1-912.

To all whom it may concern:

Be it known that we, ALEXANDER JUsT gineer, subjects of the Emperor of Austria- Hungary, residing at Desewfi'y utcza 3, Budapest, in the Empire of Austria-Hungary, have jointly invented certain new and useful Incandescent Bodies fOPElBCtIlJ Lamps,

' of which the following is a specification.

The present invention has for its object incandescing filaments for incandescent elec trio lights or lamps which are composed of I substantially pure tungsten.

Incandescing filaments of this kind may be manufactured in accordance with processes hereinafter described.

One such process is started with bodies consisting of a mixture of tungsten and organic binding media. Such bodies are carbonized and thereupon the carbon is removed by chemical means, the remaining filament or body consisting therefore purely of tungsten. Instead of using tungsten in the first step of manufacture we may also em loycompounds of tungsten.

11 order to produce filaments consisting of a mixture of tungsten and carbon, finely divided tungsten, or some tungsten compound which is readily reduced by carbon to a metal, such as tungsten oxid, tungstic acid, tungsten sulfid or the like is mixed with anorganic binding medium, such as solution of cellulose in chlorid ofzinc, collodion, coal tar, coal pitch or the like, the filaments being then formed by pressure in the usual manner and thereupon (or after a preceding denitration in case of apply- Il'l'g collodion) these filaments are carbomzed. As regards the quantity of the .tungsten' compound employed in this mix- .ture'the proportions should be determined in such a manner that in the finished fila ments sufficient carbon is present to impart the requisite strength to them as it is the carbon alone that imparts to such a filament the necessary strength for withstanding the subsequent treatment. Thus for example, eflicient filaments are obtained, if from 2 to 10 g. tun tic acid are added to a solution of 10 g. ce lulose in 260 g. 'chlorid of zinc of the specific weight of 1.83, this mixturebeing. then for'med into filaments and carbonized in absence of air. The said filaments which consist of a homogeneous filament of tungsten. These filaments then may be equalized in a manneranalogous to .into carbonic oxid, and there remains a that employed in the treatment of ordinary carbon filaments, by submitting them to the action of a current in an atmosphere of vola tile tungsten compounds inthe presence of a considerable quantity of hydrogen, so that the tungsten deposited 'equalizes the filaments. The filament-s so produced are fused 1n the customary manner into lass bulbs,

.which are then exhausted. Fina 1y tungsten incandescing filaments may be manufactured in the following manner -;As is already known, it is old to coat carbon filaments with tungsten by heating such filaments. in the vapor. of a halogen compound of this metal in the presence of a large quantityof hydrogen. The finest possible. carbon filaments (of about 0.04 mm. in diameter). are coated with a layer of sufiicient thickness of the said metal and the filaments are then treated in the following manner: The filaments are exposed in an atmosphere of neutral gases under the influence of an electric current to,

a high temperature, whereby in a few min utes the carbon contained in the core is dissolved by the metal surrounding it. This solution takes place owing to'the fact that the free carbon is absorbed by the metalas carbid. A filament treated in this manner shows itself to be perfectly homogeneous, if a point of fracture is submitted to microscopic inspection, which afl'o'rds proof that it no longer contains 1 any carbon core. These filaments may now be readily freed from carbon as described above so thatpure metal filaments are obtained.

The filaments produced according-to this invention consist of dense "coherent tungsten metal and have a high fusing point of approximately 3200" C. and are capable of incandescent efiiciency at the rate of less than 1 watt per candle power and'aresubstantially free from perce tible dlslntegration at that efiiciency, t e light-emitting properties of the filaments being due to the coherent, homogeneous metallic nature; of the tungsten. e

What we claim herein as new and desire to secure by Letters Patent is 1. A filament for incandescent 1ights "consisting of tungsten in a'c'oherent metallic state and homogeneous throughout.

2. .A filament for incandescent 1i hts consisting throughout of substantia 1y pure metallic tungsten of high fusin point and electrically conductive, the lig t emitting properties of the filament being due to the coherent; homogeneous metallic nature of the tungsten.

3; A filament for electric incandescent lights comprlsingugense, coherent tungsten: ing point approximate? metal, having its 3 200 C. and capable of incandescent e ciency at the rate of less than 1 watt per candle power and substantially free from perce tlble disintegration at that efficiency.

n testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses. o

ALEXANDER JUST.- FRANZ HANAMAN.

Witnesses:

Lnnvm ITAB0RY,'. LOUIS VANDonY. 

